Wu Honglu, Durante Marco, Furusawa Yoshiya, George Kerry, Kawata Tetsuya, Cucinotta Francis A
National Space Biomedical Research Institute, Baylor College of Medicine, NASA Johnson Space Center, Houston, Texas 77058, USA.
Radiat Res. 2003 Oct;160(4):418-24. doi: 10.1667/rr3061.
Confluent human fibroblast cells (AG1522) were irradiated with gamma rays, 490 MeV/nucleon silicon ions, or iron ions at either 200 or 500 MeV/nucleon. The cells were allowed to repair at 37 degrees C for 24 h after exposure, and a chemically induced premature chromosome condensation (PCC) technique was used to condense chromosomes in the G2 phase of the cell cycle. Incomplete and complex exchanges were analyzed in the irradiated samples. To verify that chromosomal breaks were truly unrejoined, chromosome aberrations were analyzed using a combination of whole-chromosome specific probes and probes specific for the telomere region of the chromosome. Results showed that the frequency of unrejoined chromosome breaks was higher after irradiation with the heavy ions of high LET, and consequently the ratio of incomplete to complete exchanges increased steadily with LET up to 440 keV/microm, the highest LET included in the present study. For samples exposed to 200 MeV/nucleon iron ions, chromosome aberrations were analyzed using the multicolor FISH (mFISH) technique, which allows identification of both complex and truly incomplete exchanges. Results of the mFISH study showed that 0.7 and 3 Gy iron ions produced similar ratios of complex to simple exchanges and incomplete to complete exchanges; these ratios were higher than those obtained after exposure to 6 Gy gamma rays. After 0.7 Gy of iron ions, most complex aberrations were found to involve three or four chromosomes, which is a likely indication of the maximum number of chromosome domains traversed by a single iron-ion track.
将汇合的人成纤维细胞（AG1522）用γ射线、490 MeV/核子的硅离子或200或500 MeV/核子的铁离子进行辐照。辐照后，细胞在37℃下修复24小时，然后使用化学诱导的早熟染色体凝集（PCC）技术使细胞周期G2期的染色体凝集。对辐照后的样品分析不完全和复杂的交换。为了验证染色体断裂确实未重新连接，使用全染色体特异性探针和染色体端粒区域特异性探针的组合分析染色体畸变。结果表明，高传能线密度（LET）重离子辐照后未重新连接的染色体断裂频率更高，因此，不完全交换与完全交换的比例随着LET的增加而稳步上升，直至440 keV/μm，这是本研究中包含的最高LET。对于暴露于200 MeV/核子铁离子的样品，使用多色荧光原位杂交（mFISH）技术分析染色体畸变，该技术可识别复杂和真正不完全的交换。mFISH研究结果表明，0.7和3 Gy铁离子产生的复杂交换与简单交换以及不完全交换与完全交换的比例相似；这些比例高于暴露于6 Gyγ射线后获得的比例。在0.7 Gy铁离子照射后，发现大多数复杂畸变涉及三或四条染色体，这可能表明单个铁离子轨迹穿过的染色体区域的最大数量。
